it should take 6 hours total usage time to have a good battery reach 80% of discharge (20% remaining)
try not to exceed as it can damage boards and contact tipsfrom low voltage (new machines will cut out lift and enter limp home mode to tell u it needs to charge) and dont charge too early as you will decrese the useful duty cycle over time

8 8 8 rule -
8 hour shift
8 hour charge
8 hour cooldown
chargers heat up the battery in the final charge phase to mix the water and acid properly and need a long time to cool back down to operating temp another reason y quick charges are more bad than good